This chapter overviews the application of immersive analytics to simulations of built environments through three distinct case studies. The first case study examines an immersive analytics approach based upon the concept of “Virtual Production Intelligence” for virtual prototyping tools throughout the planning phase of complete production sites. The second study addresses the 3D simulation of an extensive urban area and the attendant immersive analytic considerations in an interactive model of a sustainable city. The third study reviews how immersive analytic overlays have been applied for virtual heritage in the reconstruction and crowd simulation of the medieval Cambodian temple complex of Angkor Wat.

@Inbook{Chandler2018,author="Chandler, Tomand Morgan, Thomasand Kuhlen, Torsten Wolfgang",editor="Marriott, Kimand Schreiber, Falkand Dwyer, Timand Klein, Karstenand Riche, Nathalie Henryand Itoh, Takayukiand Stuerzlinger, Wolfgangand Thomas, Bruce H.",title="Exploring Immersive Analytics for Built Environments",bookTitle="Immersive Analytics",year="2018",publisher="Springer International Publishing",address="Cham",pages="331--357",abstract="This chapter overviews the application of immersive analytics to simulations of built environments through three distinct case studies. The first case study examines an immersive analytics approach based upon the concept of ``Virtual Production Intelligence'' for virtual prototyping tools throughout the planning phase of complete production sites. The second study addresses the 3D simulation of an extensive urban area (191 km{\$}{\$}^2{\$}{\$}) and the attendant immersive analytic considerations in an interactive model of a sustainable city. The third study reviews how immersive analytic overlays have been applied for virtual heritage in the reconstruction and crowd simulation of the medieval Cambodian temple complex of Angkor Wat.",isbn="978-3-030-01388-2",doi="10.1007/978-3-030-01388-2_11",url="https://doi.org/10.1007/978-3-030-01388-2_11"}

Personal space (PS), the flexible protective zone maintained around oneself, is a key element of everyday social interactions. It, e.g., affects people's interpersonal distance and is thus largely involved when navigating through social environments. However, the PS is regulated dynamically, its size depends on numerous social and personal characteristics and its violation evokes different levels of discomfort and physiological arousal. Thus, gaining more insight into this phenomenon is important.

We contribute to the PS investigations by presenting the results of a controlled experiment in a CAVE, focusing on German males in the age of 18 to 30 years. The PS preferences of 27 participants have been sampled while they were approached by either a single embodied, computer-controlled virtual agent (VA) or by a group of three VAs. In order to investigate the influence of a VA's emotions, we altered their facial expression between angry and happy. Our results indicate that the emotion as well as the number of VAs approaching influence the PS: larger distances are chosen to angry VAs compared to happy ones; single VAs are allowed closer compared to the group. Thus, our study is a foundation for social and behavioral studies investigating PS preferences.

In virtual environments, the space that can be explored by real walking is limited by the size of the tracked area. To enable unimpeded walking through large virtual spaces in small real-world surroundings, redirection techniques are used. These unnoticeably manipulate the user’s virtual walking trajectory. It is important to know how strongly such techniques can be applied without the user noticing the manipulation—or getting cybersick. Previously, this was estimated by measuring a detection threshold (DT) in highly-controlled psychophysical studies, which experimentally isolate the effect but do not aim for perceived immersion in the context of VR applications. While these studies suggest that only relatively low degrees of manipulation are tolerable, we claim that, besides establishing detection thresholds, it is important to know when the user’s immersion breaks. We hypothesize that the degree of unnoticed manipulation is significantly different from the detection threshold when the user is immersed in a task. We conducted three studies: a) to devise an experimental paradigm to measure the threshold of limited immersion (TLI), b) to measure the TLI for slowly decreasing and increasing rotation gains, and c) to establish a baseline of cybersickness for our experimental setup. For rotation gains greater than 1.0, we found that immersion breaks quite late after the gain is detectable. However, for gains lesser than 1.0, some users reported a break of immersion even before established detection thresholds were reached. Apparently, the developed metric measures an additional quality of user experience. This article contributes to the development of effective spatial compression methods by utilizing the break of immersion as a benchmark for redirection techniques.

During free exploration of an unknown virtual scene, users often miss important parts, leading to incorrect or incomplete environment knowledge and a potential negative impact on performance in later tasks.
This is addressed by wayfinding aids such as compasses, maps, or trails, and automated exploration schemes such as guided tours.
However, these approaches either do not actually ensure exploration success or take away control from the user.

Therefore, we present an interactive assistance interface to support exploration that guides users to interesting and unvisited parts of the scene upon request, supplementing their own, free exploration.
It is based on an automated analysis of object visibility and viewpoint quality and is therefore applicable to a wide range of scenes without human supervision or manual input.
In a user study, we found that the approach improves users' knowledge of the environment, leads to a more complete exploration of the scene, and is also subjectively helpful and easy to use.

When interacting and communicating with virtual agents in immersive environments, the agents’ behavior should be believable and authentic. Thereby, one important aspect is a convincing auralizations of their speech. In this work-in progress paper a study design to evaluate the effect of adding directivity to speech sound source on the perceived social presence of a virtual agent is presented. Therefore, we describe the study design and discuss first results of a prestudy as well as consequential improvements of the design.

Various factors influence the degree of cybersickness a user can
suffer in an immersive virtual environment, some of which can be
controlled without adapting the virtual environment itself. When
using HMDs, one example is the size of the field of view. However,
the degree to which factors like this can be manipulated without
affecting the user negatively in other ways is limited. Another prominent
characteristic of cybersickness is that it affects individuals very
differently. Therefore, to account for both the possible disruptive
nature of alleviating factors and the high interpersonal variance, a
promising approach may be to intervene only in cases where users
experience discomfort symptoms, and only as much as necessary.
Thus, we conducted a first experiment, where the field of view was
decreased when people feel uncomfortable, to evaluate the possible
positive impact on sickness and negative influence on presence.
While we found no significant evidence for any of these possible
effects, interesting further results and observations were made.

My research focuses on social locomotion of computer-controlled, human-like, virtual agents in virtual reality applications. Two main areas are covered in the literature: a) user-agent-dynamics in, e.g., pedestrian scenarios and b) pure inter-agent-dynamics. However, joint locomotion of a social group consisting of a user and one to several virtual agents has not been investigated yet. I intend to close this gap by contributing an algorithmic model of an agent’s behavior during social locomotion. In addition, I plan to evaluate the effects of the resulting agent’s locomotion patterns on a user’s perceived degree of immersion, comfort, as well as social presence.

The concept of personal space is a key element of social interactions. As such, it is a recurring subject of investigations in the context of research on proxemics. Using virtual-reality-based experiments, we contribute to this area by evaluating the direct effects of emotional expressions of an approaching virtual agent on an individual’s behavioral and physiological responses. As a pilot study focusing on the emotion expressed solely by facial expressions gave promising results, we now present a study design to gain more insight.

Fluid artwork refers to works of art based on the aesthetics of fluid motion, such as smoke photography, ink injection into water, and paper marbling. Inspired by such types of art, we created Fluid Sketching as a novel medium for creating 3D fluid artwork in immersive virtual environments. It allows artists to draw 3D fluid-like sketches and manipulate them via six degrees of freedom input devices. Different sets of brush strokes are available, varying different characteristics of the fluid. Because of fluid's nature, the diffusion of the drawn fluid sketch is animated, and artists have control over altering the fluid properties and stopping the diffusion process whenever they are satisfied with the current result. Furthermore, they can shape the drawn sketch by directly interacting with it, either with their hand or by blowing into the fluid. We rely on particle advection via curl-noise as a fast procedural method for animating the fluid flow.

In this work, we describe a hybrid, hand-based interaction metaphor that makes remote and close objects
in an HMD-based immersive virtual environment (IVE) seamlessly accessible. To accomplish this, different
existing techniques, such as go-go and HOMER, were combined in a way that aims for generality,
intuitiveness, uniformity, and speed. A technique like this is one prerequisite for a successful integration
of IVEs to professional everyday applications, such as data analysis workflows.

Cybersickness poses a crucial threat to applications in the domain of Virtual Reality. Yet, its predictors are insufficiently explored when redirection techniques are applied. Those techniques let users explore large virtual spaces by natural walking in a smaller tracked space. This is achieved by unnoticeably manipulating the user’s virtual walking trajectory. Unfortunately, this also makes the application more prone to cause Cybersickness. We conducted a user study with a semi-structured interview to get quantitative and qualitative insights into this domain. Results show that Cybersickness arises, but also eases ten minutes after the exposure. Quantitative results indicate that a tolerance towards Cybersickness might be related to self-efficacy constructs and therefore learnable or trainable, while qualitative results indicate that users’ endurance of Cybersickness is dependent on symptom factors such as intensity and duration, as well as factors of usage context and motivation. The role of Cybersickness in Virtual Reality environments is discussed in terms of the applicability of redirected walking techniques.

In this interactive demo, we present our Fluid Sketching application as an innovative virtual reality-based interpretation of traditional marbling art. By using a particle-based simulation combined with natural, spatial, and multi-modal interaction techniques, we create and extend the original artistic work to build a comprehensive interactive experience. With the interactive demo of Fluid Sketching during Mensch und Computer 2018, we aim at increasing the awareness of paper marbling as traditional type of art and demonstrating the potential of virtual reality as new and innovative digital and artistic medium.

Virtual Environments: Current Topics in Psychological Research (VECTOR) workshop, 2018

Personal Space (PS) is regulated dynamically by choosing an appropriate interpersonal distance when navigating through social environments. This key element in social interactions is influenced by numerous social and personal characteristics, e.g., the nature of the relationship between the interaction partners and the other’s sex and age. Moreover, affective contexts and expressions of interaction partners influence PS preferences, evident, e.g., in larger distances to others in threatening situations or when confronted with angry-looking individuals. Given the prominent role of emotional expressions in our everyday social interactions, we investigate how emotions affect PS adaptions.

Real walking is the most natural and intuitive way to navigate the world around us. In Virtual Reality, the limited tracking area of commercially available systems typically does not match the size of the virtual environment we wish to explore. Spatial compression methods enable the user to walk further in the virtual environment than the real tracking bounds permit. This demo gives a glimpse into our ongoing research on spatial compression in VR. Visitors can walk through a realistic model of the Aachen Cathedral within a room-sized tracking area.